PKOGKESSION ON THE LAND. 47 



of movement for which this celebrated bird is famous. Tlie 

 limb of the ostrich, with its large bones placed very obliquely 

 to form a system of powerful levers, is the very embodiment 

 of speed. The foot is quite worthy of the limb,' it being in 



Fig. 24. — Skeleton of the Ostrich. Show« the T>o\verM legs, small feet, and 

 rudimentary wings of the bird ; the obliquity at which the bones of the legs 

 and wings are placed, and the comparatively small angles which any two 

 bones make at thdr ])oint of junction, a Angle made by femur with ilium. 

 b Angle made by tibia and fibula with femur.- c Angle made by tarso- 

 metatarsal bone with tibia and fibula d Angle made by bones of foot with 

 tarso-metatarsal bone, r Bones of wing inclined to each other at nearly right 

 angles. Compare with fig. 4, p. 21, fig. 2(5, p. 55, and fig. 27, p 59.— Adapted 

 from Dallas. 



some respects the most admirable structure of its kind in 

 existence. The foot of the ostrich differs considerably from 

 that of all other birds, those of its own family excepted. 

 Thus the under portion of tlie foot is flat, and specially 

 adapted for acting on plane surfaces, particularly solids.^ The 



1 Feet designed for swimming, grasping trees, or securing prey, do not 

 operate to adv^antage on a flat surface. The awkward w^addle of the swan, 

 parrot, and eagle when on the ground affords illnstratioias. 



